A Comparative Study on Safety Design Requirements between HTGR and LWR

Abstract

SSR–2/1 defines safety objectives, safety principles, and safety concepts, which shall be met by designs of nuclear power plants (NPPs). It provides NPP designs with an up to date level of safety to help organizations involved in design, manufacture, construction, modification, maintenance, operation and decommissioning. General safety design requirements in the SSR–2/1 are defined based on the designs and technologies of light water reactors (LWRs). From the design and technology points of view, high temperature gas-cooled reactors (HTGRs) are very different from LWRs. In HTGR, the coated particle fuel is the strongest, ultimate and primary fission product barrier as opposed to the containment building in LWRs. Hence, maintaining the integrity of the coated particle fuel should be the focus of the HTGR safety design aspect. Consequently, the existing known and stable safety design requirements in SSR–2/1 are not well suited for HTGRs. The purpose of this paper is to comparatively study safety design requirements between HTGR and LWR. To achieve this objective, four important safety design requirements in the SSR–2/1, i.e. design extension condition, emergency core cooling system, functional containment, and accident management, are selected to be discussed. The study concluded that a tailored set of safety design requirements derived from those defined in SSR–2/1 should be developed by considering HTGR specific characteristics.